This invention relates to the use of a treatment composition to enhance skin health. The treatment composition includes a surfactant and silk protein that can be applied to a substrate such as a nonwoven web, such that the composition will impart adequate fluid handling properties to the substrate and will subsequently be transferred to the skin for enhancing skin health. The treatment composition may further be used as a vehicle to deliver active agents to the skin.
The skin is naturally an excellent barrier to the penetration of many foreign substances. From time-to-time, the natural ability of the skin to protect is compromised by external factors including abrasions, irritants and the like. Attempts have been made in recent years to promote skin health through the use of fiber products containing additives or developing synthetic or naturally occurring polymers that mimic or complement the properties of skin in order to maintain the skin health. An example of such a naturally occurring fiber includes silk fibers. Many attempts have been made to make skin-friendly materials from silk fibers. Manufacture of such fibers and materials therefrom, however, has been costly and difficult.
It is known that proteins naturally occurring in silk have enhancing properties when applied to skin and hair. Effective delivery of these silk proteins, as well as an active agent that can enhance or prevent damage to the underlying protective barrier of skin, is not yet known.
Enhancing skin health and delivering active agents to the skin to promote skin health has many advantages including: 1) protecting the skin and maintaining the skin in a moist state, essentially free from chapping or irritation, 2) pH buffering and barrier enhancement to maintain or enhance such base properties of skin, 3) inhibition of irritants that are suspected to promote irritant or allergic contact dermatitis, 4) maintaining the lubricity of skin, and 5) topical delivery of active agent compounds to improve utility of these compounds to improve the state of skin health.
The permeability of the skin to a foreign substance is influenced by a combination of physico-chemical parameters for both the object and the vehicle, if applicable, that delivers the object. Maintaining health of the skin and its underlying barrier properties requires optimal physico-chemical properties of the skin. The use of silk proteins such as sericin to improve these properties has never been completely optimized.
Sericin is one of two proteins that are part of the twin fibroin silk thread spun by Bombyx mori, a domestic insect. Sericin acts as a protective envelope around the fibroin thread as it is spun, which is like spinning of fibers with soluble sizing agents to help form good quality fibers. The sericin can be easily separated from silk protein by hydrolysis.
Post-spun sericin, with its unique properties, is known to have high affinity to a number of proteins. When refined to a high molecular weight substance it is amenable to binding to the keratin of skin and hair, forming a resistant, moisturizing, and protective film on the skin/hair, imparting good barrier properties.
Sericin is a silk protein obtained by controlled hydrolysis of low molecular weight silk having a specific gravity of at least about 1. A commercially available silk protein is available from Croda, Inc., of Parsippany, N.J., and is sold under the trade name CROSILK LIQUID (silk amino acids), CROSILK 10,000 (hydrolyzed silk), CROSILK POWDER (powdered silk), and CROSILKQUAT (cocodimonium hydroxypropyl silk amino acid). Another example of a commercially available silk protein is SERICIN, available from Pentapharm, LTD, a division of Kordia, bv, of the Netherlands. Further details of such silk protein mixtures can be found in U.S. Pat. No. 4,906,460, to Kim, et al., assigned to Sorenco, which is herein incorporated by reference in its entirety.
Sericin can be adapted for topical delivery by a compound that is specifically designed to provide a therapeutic effect only to the local area to which the compound is applied. Furthermore, topical formulations are often designed to prevent any systemic delivery of the compound in order to localize its use. Depending on the vehicle, topical delivery of a compound can result in predictable and reliable delivery of an agent to promote skin health.
U.S. Pat. No. 5,728,461 to Nogata et al., assigned to Seiren, Co., Ltd., discloses a protein (e.g. sericin) applied to a surface of a fiber whereby the fiber forms a textile fabric such as a tight or pantyhose. When the pantyhose was in contact with human skin, the sericin was mechanically applied/transferred to the skin to maintain the skin in a moist state, thereby preventing chapping and senescence of the skin.
European Patent Application No. 0,841,065 A2 to Yamada, et al., published May 13, 1998, discloses topically applied compositions that are useful as an antioxidant or as an inhibitor for tyrosinase activity, in order to prevent skin pigmentation or blotches caused by melanin formation.
U.S. Pat. No. 5,415,813 to Misselyn, et al., assigned to Colgate-Palmolive Company discloses the use of 0.01 to 3% of a silk protein as a skin friendly ingredient in an all-purpose liquid cleaning emulsion composition.
There is a need for a treatment composition for use with a substrate that is capable of delivering a thin, tenacious, substantially continuous film of the silk protein to the skin that can prevent or reduce skin irritation, maintain pH, maintain skin hydration, lubrication, and aid as a vehicle for the topical delivery of active agent compounds. The composition of the instant invention fulfills this need. Additionally, while skin wellness additives are known, other compositions have had the undesired side effect of reducing wettability, or the fluid intake rate, of the substrate. There remains a need for a treatment composition for application and use with a substrate that will not adversely affect fluid properties of the substrate, e.g. fast and sustainable fluid intake rate.
The present invention relates to a composition for surface treatment of a substrate, e.g. a nonwoven web, used in personal care product applications. The surface treatment combination not only provides adequate fluid handling properties, but also provides a topical delivery system effective in depositing a thin, tenacious and substantially continuous coating of a silk protein on skin by an aqueous emulsion mediated dissolution of protein from a substrate with subsequent transfer and deposition onto the skin. Coatings of silk protein on skin resist removal, thereby providing a protective barrier against chemically- and biochemically-induced skin damage. The treatment composition also provides a vehicle for administering an effective dose of an active agent to the skin surface. Also provided is a treatment composition for application and use with a substrate that will not adversely affect fluid properties of the substrate, e.g. fast and sustainable fluid intake rate as long as the material/product is being used.